Friendship is complicated. Sometimes it's based on compatibility, common interests, and shared goals and values. Sometimes friendship is more complex and political; people naturally form alliances to further personal agendas. Other good friendships are just a matter of convenience. When the girl next door is the only kid your age within a five-mile radius, chances are you're going to be buddies.

And then life happens. Children grow up. People move away. They marry (or not), have children (or not), divorce (or not). They take up different sports, become foodies, become vegan foodies, discover a previously unrecognized passion for cello, politics, or unusual fraternal organizations. In short, they change.

As individuals evolve, so do friendships. Many become richer and more rewarding for having endured change and upheaval. These enduring friendships can help those engaged in them to lead longer, healthier, and more satisfying lives.

This article is not about these relationships.

Sometimes friendships fizzle out with time and/or distance, and that's perfectly normal. In these cases, there is a mutual understanding between the parties involved that it's time to move on, and the friendship eventually becomes more of an acquaintanceship and finally, a fond and distant memory.

This article is not about these transitory bonds, either.

No, we're here to talk about a far trickier relationship that most of us have little idea how to address: the friendship that must actually and actively be ended.

If you feel you are being used, abused, taken advantage of, or ignored; if you find yourself feeling drained instead of supported after every encounter; if you just flat-out don't like someone anymore, well, it's time to end the relationship. But how?

You could let your resentment and dislike percolate to the point where — BOOM! — you're in his face, jabbing your index finger into her sternum, telling it like it is and making sure the person in question never wants to be within range of your vitriol and spittle again. But that doesn't seem very pleasant … or productive. Ending a friendship with a big blowup will only leave both parties feeling angry, unhappy, and self-righteous. Collateral personnel — other folks in your social networks and community — might be injured in the fray, and no one will have learned anything useful toward improving future relationships.

Conversely, conflict-averse types might be tempted to resort to radio silence. Cold turkey. Stop answering calls and texts. Hide when she drops by. Avoid invitations from mutual friends. Awkwardly refuse to make eye contact and mumble something about being in a hurry when you encounter each other in Trader Joe's, a strategy I like to call "den-aisle" because it doesn't work. None of these tactics really do.

Advice columns are peppered with laments from former BFFs who simply stopped hearing from people they considered to be close, and one has to feel their pain. What did I do? Why doesn't he like me anymore? How can I get my green cashmere sweater back?

Here's the truth: Platonic relationships of a certain duration and/or intensity require as much kindness and tact to end as romantic relationships do. Provided you are not the kind of amoral skeez who would simply stop calling a lover or deliberately pick a fight with your domestic partner to encourage her to move out, you owe your friend — soon to be former friend — the courtesy and honor of a proper breakup. Here's how:

1. Examine your strengths

Reflect on the positive qualities you've brought to the relationship. You are a good listener. You've got lots of life experience to share. You've always looked after her dogs when she's out of town. Even if you are feeling negatively about the relationship and your role in it, resist the urge to focus on anything but your positive contributions.

2. Acknowledge what's good about the other person

Now it's time to think about the other person and his or her strengths. This may be more difficult, but once again, stick to the good stuff. Loyalty. Intelligence. A cheerful willingness to pick up your kids when you are running late.

3. Tell the truth

Having recognized the good stuff, now allow yourself to articulate the specific reason(s) you feel the friendship is at an end. However … don't couch these in negative, accusatory terms. Try to make the issue more neutral. For example, instead of "I can't stand his constant complaining about everything," think "At this point in my life I need to be around really positive, upbeat people only." Don't dwell on the fact that the only time she ever calls you is when she needs a favor; tell yourself you've got so much going on that you just can't be available to her in the same way anymore.

4. Be brave; be fair

Now comes the really hard part. You have to break up with your friend. In person. Not a text. Not an email. If you live far away, a phone call is okay, but not ideal. Suggest you meet in a neutral place, but not a café or restaurant. As with any breakup, both parties should feel they can leave at any point without causing a fuss. A walk through a park or along a beach is good; exercise and nature alleviate stress, and this has the potential to be a stressful conversation.

Then, as you're walking, tell your friend exactly what you're thinking. This won't be easy, but bolster your courage by reminding yourself you are doing the right thing. Don't apologize; don't equivocate. Just tell the truth.

Jonathan, we met when we were both happily married. I tried to be as supportive as possible throughout your divorce, but two years later I find myself increasingly uncomfortable around you because you continue to talk about how terrible all women are, all the time. I am sorry Joanne left you; I really am. But even though I've told you I can't handle the negative rants, you can't seem to let your anger go. You are such an intelligent and hard-working guy — I hope one day you can resolve this and be happy. But in the meantime, I can't be around you anymore.

Or:

Cordelia, we've been friends since grad school, and I've always admired your ambition and drive. However, lately I've noticed you only call me when you need something or have a problem you want to talk about. I've mentioned this to you a couple of times, but it still seems to me I am less of a friend to you than someone you lean on occasionally. I need to concentrate on my own career and family more now, so I'm not going to be available in that capacity anymore.

What happens next is entirely up to the other person, who may agree with you, shake hands, and walk away; who may object, argue, or cry, or start ticking off all the reasons he doesn't want to be friends with you. Whatever happens, just let it happen. You've stated your truth — as kindly as possible — and there is no need to say anything more until it's time to say "goodbye."

5. Remember your former friend kindly

It is possible to move along from a malignant or stagnant friendship with honesty and empathy. It's not easy, but it will free you from a burden and possibly — just possibly — give your former friend an opportunity to think about his or her priorities and relationships as well. Part on good terms. Don't talk about her behind her back. Move on — and do it kindly.